Drying method of ceramic spring green body

Abstract

The preparation method of the ceramic spring comprises the following steps that (1) ceramic mud is made into a wire rod through an extrusion device, the wire rod is synchronously and spirally wound on a drying and shaping mold, and a ceramic spring wet blank is formed; (2) drying and shaping: (2.1) dipping in a moisturizing oil agent, (2.2) attaching a layer of high-elasticity plastic film on the surface of the wet ceramic spring blank to restrain the wet ceramic spring blank from structural deformation, (2.3) multi-section drying: inserting the wet ceramic spring blank bound by the high-elasticity plastic film into a rubber tube of a constant-temperature and constant-humidity chamber together with a mold, and then performing multi-section drying, and (2.4) demolding; (3) rubber discharging of the ceramic spring; and (4) putting the spring blank subjected to glue removal and the sintering clamp into sintering equipment together, and sintering in inert gas to obtain a ceramic spring blank. The drying shaping mold is a drying mold with spiral teeth, the interior of the mold is hollow, and a large number of air holes are regularly formed in the spiral teeth of the mold. According to the method, the drying effect of the green body is improved, shrinkage deformation and cracking of the ceramic green body are prevented, and accurate control over the shape and size of the ceramic is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to a drying method of a ceramic spring blank, in particular, to a preparation method of a ceramic spring, and belongs to the field of ceramic materials. BACKGROUND

[0002] With the development of aerospace technology, higher requirements are put forward for the temperature resistance and high reliability of temperature-resistant components. The temperature resistance of traditional metal and high-temperature alloy springs is low, and oxidation and corrosion easily occur in service conditions, which is difficult to meet the application requirements, so ceramic springs become the research focus.

[0003] CN108955175A (December 07, 2018) discloses a ceramic blank drying device and drying process, which divides the ceramic blank drying process into four processes of moisture preservation and heating, medium temperature hot air dehydration, high temperature dehydration and cooling. At the beginning, the ceramic blank is heated under a certain humidity to avoid cracks caused by too fast dehydration during heating, thereby improving the product quality. In the medium temperature hot air dehydration process, the medium temperature and low humidity gas is injected from the hot air branch pipe, and the exhaust branch pipe is used to exhaust the moisture in the box, so that the internal moisture of the ceramic blank can be quickly diffused outward. By simultaneously introducing hot water and hot air into the drying box, high temperature and rapid dehydration are realized. After the ceramic blank is dried, cooling water is introduced to shorten the cooling time and improve the production efficiency.

[0004] CN106500469A (March 15, 2017) discloses a ceramic drying and firing method using a programmable controller to control the kiln to complete the ceramic drying and firing. First, set the working program in the programmable controller, install the ceramic blank in the layer rack, place the layer rack on the grate at the entrance of the kiln, then start the control program, and the grate sequentially transports the layer rack with the ceramic blank to the drying chamber for drying, to the combustion chamber for firing, to the cooling chamber for cooling, and finally to the outlet of the kiln. This ceramic drying and firing method uses a layer rack to place the ceramic blank, and the programmable controller controls the grate to send the layer rack with the ceramic blank into the drying chamber and the combustion chamber for drying and firing, respectively. The furnace body is short, the occupied area is small, the working efficiency is high, and the operation is simple.

[0005] CN112209724A (2021-01-12) discloses a shape-preserving drying method for 3D printing direct writing forming ceramic green body: laying a layer of hydrophobic film on the printing base plate, 3D printing ceramic preliminary body on the hydrophobic film; the ceramic preliminary body and the printing base plate are put into a constant temperature and humidity environment together, the temperature and humidity to be set for the constant temperature and humidity drying process are selected according to the warping degree relationship formula obtained by MATLAB calculation and fitting experimental data, in the formula, w is the warping degree (%) of the ceramic preliminary body after drying, T is the corresponding constant temperature (℃), H is the relative humidity (%), S is the solid content (%), the solid content is 18-22.29%, the constant temperature selection range is 25-35℃, the relative humidity selection range is 40-92%, and the drying time is 6h; the ceramic preliminary body is separated from the hydrophobic film, and the ceramic preliminary body is continuously subjected to the above constant temperature and humidity drying process, and the drying time is 12-15h; the ceramic preliminary body is continuously subjected to the constant temperature and humidity drying process, the constant temperature is set to 25℃, the relative humidity is set to 40%, and the constant temperature and humidity drying is continued for 3h; the ceramic preliminary body after constant temperature and humidity drying is put into an oven, the temperature is set to 100℃, and the drying time is 10-20min. The shape-preserving drying method for 3D printing direct writing forming ceramic green body is used for preparing ceramic parts.

[0006] CN110128172A (2019-08-16) discloses a method for improving the moisture retention performance of ceramic tile green body and ceramic tile prepared by the method. The method comprises the following steps: step one, preparing ceramic tile green body semi-finished product; step two, glaze decoration; step three, color pattern decoration; step four, controlling the temperature, environment temperature and humidity of the body; step five, applying moisture retention agent; step six, applying adhesive on the surface of the moisture retention agent film layer; step seven, applying dry particles or powder material; step eight, spraying fixing agent; step nine, sintering. The method can prevent the subsequent adhesive from directly acting on the body surface or glaze surface, reduce the absorption and penetration time of the adhesive liquid on the body surface or glaze surface, enhance the adhesion degree of the adhesive and dry particles or powder material, greatly improve the adhesion stability of the dry particles or powder material, and obtain more stable decoration effect.

[0007] CN116178052A (2023-05-30) discloses a preparation method of fluid painting art ceramic tile, comprising: (1) pressing ceramic powder into a shape, drying to obtain a flat or mold surface ceramic tile body; (2) applying a bottom glaze; (3) spraying a film-forming moisturizer on the tile body; (4) drying with electric infrared, forming a water-blocking film layer on the surface of the tile body; (5) spraying a large amount of ink to print a design; (6) determining whether to blow air, if yes, using a blower to blow the wet ink on the surface of the tile body, so that the ink of different colors flows in different directions; if no, going to the next step; (7) determining whether to shake the glaze, if yes, using a glaze shaking cabinet to shake the glaze and form splashing texture on the surface of the tile body; if no, going to the next step; (8) sending the tile body into a hot air drying kiln for drying; (9) spraying / flowing transparent glaze decoration; (10) sending the tile body into a roller kiln for firing and polishing to obtain a fluid painting art ceramic tile product.

[0008] CN106863565A (2017-06-20) discloses a drying method of ceramic body in a drying oven, comprising the following steps: placing the ceramic body in the drying oven, first stage drying time 25-35 minutes, temperature 34-36℃, humidity 91-93% RH; second stage drying time 950-970 minutes, temperature 39-41℃, humidity 91-93% RH; third stage drying time 770-790 minutes, temperature 44-46℃, humidity 83-87% RH; fourth stage drying time 530-550 minutes, temperature 69-71℃, humidity 9-11% RH; fifth stage drying time 500-520 minutes, temperature 69-71℃, humidity 9-11% RH; sixth stage cooling time 25-35 minutes, temperature 9-11℃, humidity 9-11% RH. The drying method has the advantages of short time consumption and low ceramic body cracking rate.

[0009] CN106288747A (2017-01-04) discloses a method for drying ceramic green body by pulse air supply, the drying process comprises one or more identical air supply cycles; each air supply cycle comprises a forward air supply part and a reverse air supply part, the air supply direction of the forward air supply part is opposite to that of the reverse air supply part. Preferably, the forward air supply part or the reverse air supply part of each air supply cycle comprises one or more low air speed air supply stages and one or more high air speed air supply stages. Specifically, the forward air supply part or the reverse air supply part of each air supply cycle is composed of the following stages: the first stage: the absolute value of air speed is rapidly increased from zero to low air speed, and the duration is a first time period; the second stage: the absolute value of air speed is rapidly increased from low air speed to high air speed, and the duration is a second time period; the third stage: the absolute value of air speed is rapidly decreased from high air speed to low air speed, and the duration is a third time period; the fourth stage: the absolute value of air speed is rapidly increased from low air speed to high air speed, and the duration of high air speed state is a fourth time period; the fifth stage: the absolute value of air speed is slowly decreased from high air speed to zero, and the duration of the decreasing process is a fifth time period. Drying for ceramic green body.

[0010] CN105503254A (2016-04-20) discloses a method for preparing barium titanate foam ceramic: 100 parts of nano barium titanate and 30-120 parts of organic binder aqueous solution with a concentration of 1-15 wt% are fully ground, then 10-80 parts of organic rheological agent aqueous solution with a concentration of 0.5-3 wt% is added, fully ground, and then 20-80 parts of organic dispersant aqueous solution with a concentration of 0.5-3 wt% is added, fully ground to obtain a slurry; a polymer sponge is immersed in a sodium hydroxide aqueous solution with a concentration of 5-20 wt%, heated to 50-75 °C and kept for 2-6 h, then washed with deionized water and spun dry to obtain polymer sponge D; the polymer sponge D is immersed in a surfactant aqueous solution with a concentration of 0.5-3 wt% at room temperature, stays for 2-6 h, is spun dry and dried to obtain pretreated polymer sponge E; the pretreated polymer sponge E is immersed in the slurry, placed at room temperature for 1-10 min for slurry coating treatment, and after the excess slurry is squeezed out, dried at 40-80 °C, and the slurry coating and drying treatment is repeated 1-7 times to obtain a barium titanate foam ceramic green body; the barium titanate foam ceramic green body is heated from room temperature to 100-300 °C at a rate of 0.5-5 °C / min, then heated to 500-700 °C at a rate of 0.5-5 °C / min and kept for 0.5-2 h, then heated to 1000-1500 °C at a rate of 2-10 °C / min and kept for 1-5 h, and finally cooled to room temperature with the furnace.

[0011] CN113105223A (2021-07-13) discloses a method for preparing high-permeability flux whisker-shaped ceramic membranes by phase inversion-high temperature sintering: natural mineral bauxite and fly ash are ball milled, the particle size of the treated bauxite is mainly distributed in 1.23-4.56 μm, and the particle size of the fly ash is mainly distributed in 0.69-5.20 μm; polyether sulfone, N-methyl pyrrolidone and polyvinyl pyrrolidone are ball milled in a mass ratio of 6-10:24-80:1 to form a polymer slurry; the fly ash, bauxite and tungsten oxide powder are mixed into a mixed powder, the tungsten oxide powder accounts for 25-50 wt.% of the mixed powder, and the fly ash and bauxite are weighed according to the molar ratio of Al2O3:SiO2 of 3:2; the mixed powder is added to the polymer slurry, the solid content is 40-60 wt.%, and ball milling is carried out for 48-60 h to obtain a casting solution; the casting solution is vacuum degassed, then poured into the slurry tank of the spinning device, the inner core liquid is deionized water, the casting solution is extruded through the spinning head into the outer coagulation bath of 60-90 vol.% ethanol, and the mullite ceramic green body is formed by gelation and solidification; the mullite ceramic green body is naturally dried, and then sintered: first heated to 200℃ for 30 min, then heated to 600℃ for 30 min, and then heated to 1100-1500℃ for 2 h.

[0012] CN110950674A (2020-04-03) discloses a preparation method of fiber-reinforced sanitary ceramic body, comprising: 1, body preparation: 1) according to mass percentage, the body material comprises the following components: calcined bauxite 50-70%, quartz 8-16%, ball clay 2-10%, kaolin 2-7%, water-washed porcelain clay 6-14%, waste mud 5-15%, brucite fiber 1-5%, aluminum fluoride 1-3%; the raw materials are loaded into a horizontal ball mill, then an appropriate amount of alkali and water are added for wet milling and mixing until the proportion of <10 μm is 52-56%, then 0.5-1% of lignocellulose is added for further ball milling until the proportion of <10 μm is 58-61%, and then the slurry is discharged from the mill; then iron removal, sieving, refining and aging are carried out to prepare a mud slurry for standby use; 2) the mud slurry is injected into a gypsum mold for molding, and after eating slurry, consolidation and demolding, natural air drying or drying at 50-60℃ until the water content is below 5% to obtain a sanitary ceramic green body; 2, sintering: the dried ceramic body is placed in a muffle furnace for sintering; the sintering system is: the temperature is raised from room temperature to 470-500℃ at a rate of 4-6℃ / min and kept for 20-40 min, then the temperature is raised to 900-950℃ at a rate of 3-5℃ / min, and finally the temperature is raised to 1200-1250℃ at a rate of 1.5-2.5℃ / min and kept for 15-25 min. It is used for preparing large-size ultra-thin ceramic products.

[0013] CN114656287A (2022-06-24) discloses a method for preparing pseudobrookite type crystalline glaze from gold tailings, which belongs to the technical field of glaze preparation. The steps are as follows: take the middle white clay and place it on the gypsum board, press it into a round piece, dry it, and then perform the biscuit firing. After grinding the biscuit firing product, a ceramic biscuit is obtained. Prepare the TiO2 glaze with W630 or W830 as the base glaze, stir evenly with water, and obtain the crystalline glaze. Dip one side of the ceramic biscuit into the crystalline glaze to obtain the glazed biscuit. The glazed biscuit is fired in three stages with gradient temperature rising. The first stage temperature is 500-600℃, the second stage temperature is 800-1000℃, and the third stage temperature is 1220-1240℃. After cooling to room temperature, the pseudobrookite type crystalline glaze is obtained.

[0014] CN112876267A (2021-06-01) discloses a manufacturing method of a ceramic roller for a tempered glass kiln: the weight ratio of the raw materials is as follows: mullite 20-40 parts, alumina 20-45 parts, refractory clay 6-18 parts, kaolin 8-20 parts, zirconium silicate 3-10 parts, talc 0.8-2.0 parts, vanadium pentoxide 0.4-2.5 parts, boron nitride 1.2-2.8 parts, and magnesium oxide 0.4-1.8 parts; the alumina, refractory clay, kaolin, zirconium silicate, talc, vanadium pentoxide, boron nitride, and magnesium oxide are ball milled for 6-10 hours, then the mullite is added and ball milled for another 30 minutes; the obtained mixture is spray dried, stirred with water, pugged, and extruded into a green body; the green body is dried, isostatically pressed, naturally aired for 36-48 hours, dried, and finally sintered: first, heated to 400℃ at a rate of 0.5-1.5℃ / min, kept at this temperature for 30 minutes, then heated to 1000℃ at a rate of 2.5-4℃ / min, kept at this temperature for 50-120 minutes, then heated to 1150℃ at a rate of 0.2℃ / min, then heated to 1200℃ at a rate of 2.5℃ / min, and kept at this temperature for 4.5-7 hours.

[0015] CN111646819A (2020-09-11) discloses a preparation method of an environmentally friendly ceramic glaze: ball milling the base glaze raw materials and the surface glaze raw materials to prepare a base glaze slurry of 35-50 Bé and a surface glaze slurry of 60-75 Bé; pretreating the ceramic body, then applying the base glaze slurry, naturally drying for 3-4 h, and then microwave drying for 4-6 min to obtain ceramic body a; continuously applying the surface glaze slurry on the ceramic body a, naturally drying for 4-6 h, and then microwave drying for 6-8 min to obtain ceramic body b; moving the ceramic body b to a kiln, heating to 550-650℃ at a rate of 10-20℃ / min under a reducing atmosphere, maintaining for 20-25 min, then heating to 950-1050℃ at a rate of 20-30℃ / min and maintaining for 15-20 min, and finally heating to 1250-1350℃ at a rate of 2.0-3.0℃ / min and maintaining for 10-15 min. The base glaze raw materials include, by weight, 10-20 parts of sodium feldspar, 5.5-7.5 parts of calcite, 10.5-13 parts of talc, 8-12 parts of modified kaolin, 1-3 parts of vanadium oxide, and 0.5-1.5 parts of calcium oxide; the surface glaze raw materials include, by weight, 10-16 parts of sodium feldspar, 3-6 parts of potassium feldspar, 6.5-8.5 parts of talc, 2.3-4.3 parts of iron oxide, 0.5-0.8 parts of zirconium oxide, 2.4-4.4 parts of barium carbonate, and 0.4-0.7 parts of calcium oxide.

[0016] CN106365691A (2017-02-01) discloses a ceramic production method with simple operation and a sub-matte light yellow-green antique effect formed by kiln variation during firing. A sodium sulfate solution is sprayed on the surface of a ceramic body, and zinc oxide, feldspar, light magnesium carbonate, calcium carbonate, kaolin, and titanium dioxide are mixed and ball milled to form a glaze slurry. The glazed ceramic body is dried at 120℃, then heated to 950℃ at a rate of 80-140℃ / h, then heated to 1258-1260℃ at a rate of 60-80℃ / h, maintained for 1-2 h, then cooled to 1150℃ at a rate of 30-60℃ / h, then cooled to 1050℃ at a rate of 60-80℃ / h, and then naturally cooled in the kiln to obtain an antique glaze ceramic product.

[0017] CN105565899A (2016-05-11) discloses a method for preparing semi-transparent honeycomb ceramic with visible light catalytic function: mixing ultrafine α-Al2O3 with appropriate amount of Mg and XT nitrate, calcining after wet ball milling at 350-500℃, then mixing with additives and distilled water, kneading, vacuum degassing and practicing 2-3 times, and aging at room temperature for 20-30h to form plastic paste, extruding through a mold to form a wet green body; drying the wet green body by radio frequency, and then performing secondary sintering, first calcining in air atmosphere, heating to 1100-1300℃ at a rate of 230-260℃ / h, keeping for 2h, cooling to room temperature, second calcining in hydrogen flow protection or vacuum, heating to 380-420℃ from room temperature at a rate of 80-120℃ / h, then heating to 1400-1600℃ at a rate of 50-80℃ / h, and then heating to 1700-1900℃ at a rate of 20-40℃ / h, keeping for 1-3h, and then cooling, to obtain semi-transparent three-dimensional honeycomb ceramic; preparing XT and N co-doped TiO2 sol, and then loading the wet film on the honeycomb ceramic carrier by dip-coating method, drying, and heat treating at 300-700℃ to obtain semi-transparent honeycomb ceramic product loaded with XT and N co-doped TiO2 photocatalytic film. The semi-transparent honeycomb ceramic can be used for treating pollution by using sunlight.

[0018] CN104402517A (2015-03-11) discloses a method for preparing Al2O3-SiC foam ceramic: 1. mixing 60-85wt% of α-Al2O3, 5-15wt% of carbon source and 10-30wt% of elemental silicon to prepare a mixture; 2. putting 100 parts of mass of the mixture, 0.5-2 parts of mass of ammonium lignosulfonate, 0.1-0.6 parts of mass of polycarboxylate and 20-30 parts of mass of water into a stirrer, stirring for 20-30min to prepare slurry I; and then putting 100 parts of mass of solid raw material, 0.5-2 parts of mass of ammonium lignosulfonate, 0.1-0.6 parts of mass of polycarboxylate and 30-40 parts of mass of water into a stirrer, stirring for 20-30min to prepare slurry II; 3. immersing polyurethane sponge into slurry I, extruding or slushing after immersion, drying at 90-110℃ for 12-24h to obtain pretreated foam ceramic green body; spraying slurry II on the pretreated foam ceramic green body, spraying flow being 3-5L / min, spraying time being 5-30min, and then drying at 90-110℃ for 12-24h to obtain foam ceramic green body; 4. putting the foam ceramic green body into a high temperature furnace, heating to 200℃ at a rate of 1.5-2.5℃ / min under carbon-embedded atmosphere, heating to 700℃ at a rate of 0.5-1℃ / min, then heating to 1300-1500℃ at a rate of 2.5-3.5℃ / min, keeping for 2.5-3.5h, and then cooling to room temperature with the furnace, to obtain Al2O3-SiC foam ceramic.

[0019] CN107857577A (March 30, 2018) discloses a method for preparing Al2O3-ZrO2-based foam ceramics: 100 parts by weight of alumina micro powder and 50-130 parts by weight of silica sol are stirred for 20-30 minutes to obtain slurry I; 55-80 parts by weight of zirconium oxide micro powder, 20-45 parts by weight of alumina micro powder, and 5-8 parts by weight of additives are mixed to obtain mixed powder I; then 0.1-0.6 parts by weight of polycarboxylate, 0.3-2 parts by weight of ammonium lignosulfonate, 0.1-0.5 parts by weight of octanol and 22-47 parts by weight of water are added, and the mixture is ball-milled for 1-3 hours to obtain slurry II; polyurethane foam is then subjected to vacuum molding... The preform is immersed in slurry I, followed by compressed air blowing or centrifugal spinning, and then naturally dried for 12–24 hours to obtain a pre-made green body. The pre-made green body is then vacuum impregnated with slurry II, followed by compressed air blowing or centrifugal spinning, and then naturally dried. It is then baked at 70–100℃ for 12–24 hours to obtain an Al2O3-ZrO2-based foam ceramic green body. The Al2O3-ZrO2-based foam ceramic green body is placed in a high-temperature furnace and heated to 200℃ at a rate of 1–2℃ / min under air atmosphere, then to 680℃ at a rate of 1℃ / min, and then to 1350–1750℃ at a rate of 2–3℃ / min, held at that temperature for 2–5 hours, and finally cooled in the furnace. The additives are one or more of yttrium oxide micro powder, calcium oxide micro powder, or magnesium oxide micro powder.

[0020] CN105198474A (December 30, 2015) discloses a method for preparing a visible light translucent three-dimensional honeycomb ceramic mesh: the raw materials are alumina, sintering aid, binder, lubricant, defoamer, and distilled water; the binder is hydroxypropyl cellulose or hydroxymethyl (or ethyl) cellulose; the lubricant is glycerol, ethylene glycol, or glycerol; and the defoamer is n-butanol or ethanol. The raw materials are mixed and kneaded, then degassed and kneaded 2-3 times under vacuum, and aged at room temperature for 20-30 hours to form a plastic clay. The plastic clay is extruded through a mold to obtain a wet green body, which is then radio frequency dried at 195-210℃. The dry body is obtained in 4-0.5 hours and finally cut into three-dimensional honeycomb ceramic mesh dry bodies with a thickness of 6-15 mm. The dry body sample is placed in the furnace and fired according to the following firing regime: the temperature is raised from room temperature to 380-420℃ at 80-120℃ / h, then raised to 1400-1600℃ at 50-80℃ / h, then raised to 1700-1900℃ at 20-40℃, held at 1700-1900℃ for 1-3 hours, then cooled to 1100-1300℃ at 300℃ / h, then cooled to 300-500℃ at 150℃ / h, and then cooled to room temperature at 40-50℃ / h.

[0021] CN109761592A (2019-05-17) discloses an Al2O3-ZrO2-based foam ceramic with a multi-level pore structure, the preparation method of which is as follows: 1. Al2O3 micropowder (60-80 parts by mass) and ZrO2 micropowder (20-40 parts by mass) are mixed to obtain mixed powder I, then a dispersing agent (0.1-1 parts by mass), a thickening agent (0.3-1 parts by mass), a binding agent (0.1-0.5 parts by mass), and water (20-50 parts by mass) are added to the mixed powder I, and mechanical ball milling is performed for 30-60 min to obtain slurry I; 2. Al2O3 micropowder (50-70 parts by mass), ZrO2 micropowder (20-40 parts by mass), and a pore-forming agent (10 parts by mass) are mixed to obtain mixed powder II, then a dispersing agent (0.1-0.8 parts by mass) and water (30-55 parts by mass) are added to the mixed powder II, and mechanical ball milling is performed for 1-1.5 h to obtain slurry II; 3. Polyurethane sponge is immersed in slurry I at room temperature, then compressed air is sprayed or slurry is spun off by centrifugation after impregnation, and then natural drying is performed, followed by heating to 600-850 ℃ and holding to obtain an Al2O3-ZrO2-based preform; then the preform is subjected to secondary negative pressure impregnation with slurry II, air blowing or slurry spinning by centrifugation is performed after impregnation, and then vacuum freezing drying is performed at -50 to -10 ℃ and 0.5 Pa to obtain an Al2O3-ZrO2-based foam ceramic green body with a multi-level pore structure; 4. The Al2O3-ZrO2-based foam ceramic green body with a multi-level pore structure is placed in a high-temperature furnace, heated to 200 ℃ in an air atmosphere, then heated to 650 ℃, and then heated to 1400-1600 ℃ at a rate of 2-3 ℃ / min, held, and cooled to room temperature with the furnace to obtain the product. The pore-forming agent is one or a mixture of more than one of rice husk powder, inorganic carbon, polystyrene, and starch.

[0022] CN109748597A (2019-05-14) discloses a method for preparing mullite porous ceramic by mutual gelation of precursors: ρ-Al2O3 powder is added to SiO2 sol with a concentration of 10 to 20 wt%, the molar ratio of ρ-Al2O3 and SiO2 is controlled at 3:2, and the total solid content of ρ-Al2O3 and SiO2 is 28.4 to 47.2 wt%. Then the stirred slurry is placed in a vacuum degassing machine to remove air bubbles. The slurry after removing air bubbles is poured into a mold and cured at room temperature for 1 to 7 days to form a porous ceramic green body, then the porous ceramic green body is removed from the mold and placed in a drying oven at 70 ℃ for 24 h, then the dried ceramic green body is heated to 300 ℃ at a rate of 1 to 3 ℃ / min in an air atmosphere, held for 1 h, then heated to 1410 to 1440 ℃, held for 6 h to completely convert the silicon dioxide into cristobalite phase, and then heated to 1500 to 1650 ℃, held for 2 to 5 h to obtain mullite porous ceramic.

[0023] CN105419328A (2016-03-23) discloses a preparation method of modified barium titanate foam ceramic / thermosetting resin composite material, which comprises the following steps: 1, grinding nano barium titanate with aqueous solution of organic binder, adding aqueous solution of organic rheological agent for grinding, adding aqueous solution of organic dispersing agent, and grinding to obtain slurry C; 2, immersing 15-35 PPI polymer sponge in aqueous solution of sodium hydroxide, heating and keeping warm, and washing with deionized water to obtain polymer sponge D; immersing in surfactant to obtain pretreated polymer sponge E; 3, immersing in slurry C, hanging and drying to obtain barium titanate foam ceramic green body; 4, heating from room temperature to 100-300 ℃ at a rate of 0.5-5 ℃ / min, then heating to 500-700 ℃ at a rate of 0.5-5 ℃ / min and keeping warm, and heating to 1000-1500 ℃ at a rate of 2-10 ℃ / min and keeping warm to obtain barium titanate foam ceramic; 5, preparing 0.5-10 g / L dopamine solution; adjusting pH value to 8.3-8.8 with alkali to obtain solution F; immersing foam ceramic to obtain dopamine modified barium titanate foam ceramic; 6, adding 4-20 parts of 0.1-1 wt% aqueous solution of stabilizer to 100 parts of 0.03-0.3 mol / L silver ammine solution to obtain solution G; immersing dopamine modified barium titanate foam ceramic in solution G, and placing at room temperature for 0.5-24 h to obtain nano silver loaded barium titanate foam ceramic, then adding 50-300 parts of 1-30 g / L aqueous solution of reducing agent, and placing at room temperature for 0.1-5 h, and then washing with deionized water and drying to obtain modified barium titanate foam ceramic; 7, pouring molten heat-curable resin into modified barium titanate foam ceramic, heat curing, and post-treatment.

[0024] In addition, CN103386486A (2013-11-13) discloses a preparation method of a free-standing porous metal film, which comprises the following steps: 1) uniformly ball-milling a metal powder and an aqueous polyvinyl alcohol solution to obtain a slurry; 2) coating the slurry on a substrate surface, drying, and then peeling off the metal film layer to obtain a free-standing metal film blank; and 3) placing ceramic fillers and the free-standing metal film blank into a sintering mold, and performing multi-stage sintering in a sintering furnace to form a free-standing porous metal film. -2 The preparation method comprises the following steps: 1) uniformly ball-milling a metal powder and an aqueous polyvinyl alcohol solution to obtain a slurry; 2) coating the slurry on a substrate surface, drying, and then peeling off the metal film layer to obtain a free-standing metal film blank; 3) placing ceramic fillers and the free-standing metal film blank into a sintering mold, and ensuring that the ceramic fillers completely cover the free-standing metal film blank; and 4) placing the sintering mold in a sintering furnace, and performing pre-sintering pretreatment, pre-sintering treatment, sintering treatment, and cooling treatment on the free-standing metal film blank under the condition that the vacuum degree is not greater than 1×10

[0025] CN108069716A (2018-05-25) discloses a method for preparing a bronze-colored ceramic artwork: by weight parts, potassium dichromate 17-23 parts, blue vitriol 10-15 parts, pyrite stone 30-40 parts are mixed, wet ball milling 1-2 h, the slurry is aged for 24-36 h, and then sieved through a 100-200 mesh screen to obtain a slurry; by weight parts, nano-silicon dioxide modified acrylate 5-15 parts, elastic silicone acrylic emulsion 3-6 parts, silicone modified phenolic epoxy vinyl ester resin 6-10 parts are mixed with the slurry, then calcined at 1250-1350°C, crushed and finely ground to obtain a colorant; the colorant is mixed with lime glaze at a mass ratio of 1:5-6, then sieved through a 250 mesh screen to obtain a bronze-colored glaze; immerse the ceramic green body in the transparent glaze slurry for 6-15 seconds, so that the thickness of the ceramic surface glaze layer reaches 3-10 mm, then take it out and dry, load the kiln, raise the temperature from room temperature to 910-970°C at a rate of 110-210°C / h, adjust the heating rate to 30-50°C / h, raise the temperature to 1200-1350°C, stop the fire, and naturally cool to obtain a ceramic semi-finished product; immerse the ceramic semi-finished product in the bronze-colored glaze for 3-12 seconds, take it out and dry, place it in the kiln, introduce nitrogen, raise the temperature to 400-460°C within 30 min, continue to raise the temperature to 720-830°C within 30 min, and then raise the temperature to 1100°C and fire for 1-3 h. It is used for preparing a bronze-colored ceramic artwork.

[0026] CN111348907A (2020-06-30) discloses a method for preparing a matte bean green glaze antique porcelain, which comprises a body and a glaze; the body comprises sodium feldspar, Dehua quartz, Dehua kaolin, sericite, andalusite, serpentine, calcium oxide, zinc oxide, and zirconium oxide; the glaze comprises Dehua quartz, montmorillonite, diopside, iron oxide, titanium oxide, nickel oxide, yttrium oxide, and matte frit. The preparation steps include: the body raw materials are respectively crushed, mixed, wet ball milled, and aged to prepare a coarse body; the glaze raw materials are respectively crushed, mixed, and wet ball milled to prepare a glaze slurry; the prepared coarse body is placed in a kiln, and is bisque fired at 780-820°C for 5-6 h to obtain a ceramic bisque; the glaze slurry is applied to the surface of the ceramic bisque, and after the glaze slurry on the surface of the ceramic bisque is dried, it is sent into the kiln and fired at 1250-1280°C to form a shape. The glaze contains manganese carbonate. The firing is controlled by stage temperature variation, and the product is naturally cooled.

[0027] CN102276285A (2011-12-14) discloses a method for preparing porous β-SiAlON ceramic, the raw materials are Si powder: Al2O3 powder = 50-80%: 20-50% by mass, Y2O3 (Sm2O3) as sintering aid is added at 0-3% of the total mass of Si powder and Al2O3 powder; agate balls are used as grinding balls, the mass ratio of powder to agate balls is 1:1, and the mixture is placed in a nylon tank and mixed for 12-24 h by a rolling ball mill to prepare a slurry; the slurry is dried in a drying oven, granulated, and molded; the dried ceramic powder is molded on a press at a pressure of 50-200 MPa; the molded block is placed in a furnace for nitriding, the temperature is raised in stages under a flowing nitrogen atmosphere at 0.3-1 MPa, the final temperature is raised to 1250-1350°C, the holding time is 2-4 h, the nitrided sample is further heated to 1600-1800°C for sintering, the holding time is 0.5-3 h; the temperature is cooled to 500-1000°C, the nitrogen is turned off, and the sample is cooled to room temperature to obtain the product.

[0028] CN111646819A (2020-09-11) discloses a method for preparing an environmentally friendly ceramic glaze: the bottom glaze raw materials and the surface glaze raw materials are ball milled to prepare a bottom glaze slurry and a surface glaze slurry; the ceramic body is pretreated, then the bottom glaze slurry is applied, naturally dried, then microwave dried, the surface glaze slurry is applied, naturally dried, then microwave dried, and finally heated to 550-650°C under a reducing atmosphere, held for a certain time, then heated to 950-1050°C, held for a certain time, and finally heated to 1250-1350°C. The bottom glaze raw materials include sodium feldspar, calcite, talc, modified kaolin, vanadium oxide, and calcium oxide; the surface glaze raw materials include sodium feldspar, potassium feldspar, talc, iron oxide, zirconium oxide, barium carbonate, and calcium oxide.

[0029] CN110253734A (2019-09-20) discloses a method for quickly drying the micro-deformation of ceramic blanks, which comprises: wrapping the ceramic blanks to be dried with wet paper; placing on a first drying plate covered with a first filter cloth, then covering with a second filter cloth; pressing on a second drying plate; moving into a constant temperature and humidity box, turning on the internal circulating fan; drying in six stages: the first stage, the temperature is 50-60℃, the relative humidity is 80-90%, the drying time is 30-60min; the second stage, the temperature is 70-80℃, the relative humidity is 85-95%, the drying time is 60-120min; the third stage, the temperature is 85-95℃, the relative humidity is 90-95%, the drying time is 400-600min; the fourth stage, the temperature is 85-95℃, the relative humidity is 70-80%, the drying time is 180-300min; the fifth stage, the temperature is 80-95℃, the relative humidity is 45-60%, the drying time is 30-120min; the sixth stage, the body to be dried is moved into an oven, the temperature is set to 60-75℃, and the drying time is 30-120min. The dried ceramic blanks have the advantages of small warping deformation and short drying cycle.

[0030] CN1792995A (2006-06-28) discloses a drying method for ceramic and cermet blanks, which comprises: drying the blanks in a drying box and then microwave heating, repeating the cycle, while reducing the relative humidity of the drying box in stages until the water content in the blanks is not more than 5%. Specifically, the method is to repeat the cycle of wet air drying-microwave heating-wet air drying about ten times under certain temperature and relative humidity conditions until the water content in the blanks is 5-20% for semi-dry state blanks; then repeat the cycle of wet air drying-microwave heating-wet air drying about thirty times under certain temperature and relative humidity conditions until the water content in the blanks is not more than 5%.

[0031] CN104402522A (2015-03-11) discloses a method for preparing porous ceramics by heavy gas protection direct foaming method, which weighs ceramic powder, deionized water, dispersant, regulator, organic monomer and crosslinking agent, mixes and ball mills, then removes air from water-based ceramic slurry in vacuum, and adds surfactant; the slurry is put into the cavity of heavy gas protection foaming device, heavy gas is introduced into the environmental container (8) through the air pipe, the flow of the heavy gas protection foaming device, the rotating speed of the stirrer (1) and the foaming time are controlled; the four methyl hexane diamine aqueous solution and the ammonium persulfate aqueous solution are dropped into the foamed ceramic slurry from the feeding port (12), and after stirring, the foamed ceramic slurry is poured into a mold made of non-water-permeable and non-setting material; the foamed ceramic slurry is gelled and solidified in 5-60 minutes at an ambient temperature <40℃; after being placed and dried, the ceramic body is sintered by using a sintering system of slow and continuous staged temperature rise.

[0032] CN105130445A (2015-12-09) discloses a method for sintering silicon carbide-based composite ceramic green body after connection, which immerses silicon carbide body adhesive sheet in phenolic resin alcohol solution, takes out the silicon carbide body adhesive sheet, and then places it between the silicon carbide composite material green bodies to connect under the pressure of 1MPa-5MPa, and then dries and heat treats the connected silicon carbide composite material green bodies; the obtained green bodies are sintered under the conditions that the sintering atmosphere is argon or nitrogen, the atmosphere pressure is 0.1MPa-0.5MPa, the temperature rising speed is controlled, and the sintering is divided into stages. Specifically, the method comprises: 1. preparation of silicon carbide body adhesive sheet: mixing alumina or aluminum nitride, silicon carbide, carbon, silicon and yttrium oxide to obtain silicon carbide body adhesive composite powder; 2. preparation of phenolic resin alcohol solution: mixing phenolic resin, urotropine, silicon powder and anhydrous ethanol, and mechanically stirring to obtain the phenolic resin alcohol solution; 3. connection of silicon carbide-based composite material green body: immersing the silicon carbide body adhesive sheet in the phenolic resin alcohol solution, taking out the silicon carbide body adhesive sheet, and then placing it between the silicon carbide composite material green bodies to connect under the pressure of 1MPa-5MPa, and then drying and heat treating the connected silicon carbide composite material green bodies under room temperature conditions; 4. under the conditions that the sintering atmosphere is argon or nitrogen and the atmosphere pressure is 0.1MPa-0.5MPa, the connected silicon carbide composite material green bodies are heated from room temperature to 1250℃-1450℃ at a temperature rising speed of 3℃ / min-20℃ / min, and are kept warm for 30min-90min; 5. further heating to 1800℃-2100℃ at a temperature rising speed of 3℃ / min-20℃ / min, and keeping warm for 60min-180min, and then cooling to room temperature with the furnace, to obtain silicon carbide ceramic. The method is used for preparing large-size high-density parts or complex structure silicon carbide-based composite ceramics.

[0033] The above-mentioned patents all use a segmented temperature rising process in the green body drying stage to ensure uniform humidity drop in the green body, but the ceramic spring structure of the present patent is a spiral line structure with large internal stress, and only segmented drying steps are performed, which leads to fast surface drying, non-uniform humidity inside and outside the line, uneven shrinkage, and easy cracking of the line surface. At the same time, under the action of the internal stress of the spring line, the line is broken.

[0034] Therefore, the prior art cannot protect the surface of the ceramic spring green body from cracking during the rapid drying process, and thus the rapid shrinkage of the green body leads to the breaking of the spring wire, and the spring structure cannot be guaranteed not to deform during drying. SUMMARY

[0035] The purpose of the present application is to protect the surface of the ceramic spring green body from cracking during the rapid drying process, to avoid the rapid shrinkage of the green body leading to the breaking of the spring wire, and to guarantee that the spring structure does not deform during drying.

[0036] According to a first aspect of the present application, a method for preparing a ceramic spring is provided, wherein a multi-stage drying process is used to avoid cracking of the green body surface. The method for preparing the ceramic spring comprises the following steps:

[0037] 1. Preparation of ceramic spring wet green body

[0038] The ceramic powder and sintering aid are ground together in a mill, and then the ground mixture is placed in a mixing device (such as an internal mixer) to which a binder, a dispersing agent and water are added for thorough mixing, forming a ceramic mud (i.e., a slurry or a mud segment, which has plasticity and moisture retention). The ceramic mud is aged (for example, for 36-72 hours, such as 40-60 hours, or 50-55 hours), and then formed into a wire by an extrusion device and simultaneously spiral-wrapped on a (silicone oil coating has been coated on the surface of) drying shaping mold (preferably, a hollow mold with a large number of air holes) to form a ceramic spring wet green body. Preferably, the shaping mold has been coated with a silicone oil coating on its surface before use.

[0039] 2. Drying and shaping of the ceramic spring green body

[0040] (2.1) Impregnation of moisture-retaining oil agent

[0041] The ceramic spring wet green body obtained in step 1 is placed in a moisture-retaining oil agent together with the mold for impregnation (for example, for 2-3 hours), taken out and placed in a cool place to dry (to allow excess moisture-retaining oil agent to drip off), thereby forming an oil film on the surface of the wet green body. Generally, after the oil film is formed on the surface of the ceramic wet green body, a small amount of water is exuded from the ceramic wet green body, reducing the humidity inside and outside the line, and the ceramic spring wet green body is simply hardened on the surface.

[0042] (2.2) Film coating

[0043] A thin film of high-elasticity plastic (e.g. polyethylene film or ethylene-propylene copolymer film) is attached to the surface of the ceramic spring green body, and the green body is restrained from structural deformation.

[0044] (2.3) Multi-stage drying

[0045] The ceramic spring green body, which has been restrained by the thin film of high-elasticity plastic, is inserted into a rubber tube of a constant-temperature and constant-humidity chamber (e.g. a constant-temperature and constant-humidity fan) together with the mold, and then subjected to multi-stage drying (in which drying is performed in different stages in a flowing gas atmosphere of different humidity and different temperature):

[0046] First stage: air-drying is performed (e.g. for 8-12 hours, such as 10 hours) under conditions of humidity 80-90% and temperature 10-20°C (i.e. 10°C≤ temperature≤ 20°C), allowing the green body to harden.

[0047] Second stage: air-drying is performed (e.g. for 5-6 hours) under conditions of humidity 50-70% and temperature 20-40°C (i.e. 20°C≤ temperature≤ 40°C), and the green body shrinks significantly. The temperature can be moderately reduced during this process to slow the rate of shrinkage.

[0048] Third stage: air-drying is performed (e.g. for 2-3 hours) under conditions of humidity 20-40% and temperature 40-60°C (i.e. 40°C≤ temperature≤ 60°C), to obtain a substantially dried ceramic spring green body. The high-elasticity plastic film on the surface is removed.

[0049] Fourth stage: the substantially dried ceramic spring green body is placed in an oven and air-dried (e.g. for 2-30 hours, such as 3-10 hours or 5-20 hours) at a temperature of 60-70°C, until the internal moisture of the spring green body is completely dried.

[0050] (2.4) Demolding (removal of the mold)

[0051] The mold is removed (demolding or demolding), to form a ceramic spring green body.

[0052] 3. Debinding of the ceramic spring

[0053] The ceramic spring green body is fixed in a sintering jig and placed in a debinding furnace (at a temperature in the range of 100-700°C, preferably 150-650°C, more preferably 200-600°C) for air debinding, to obtain a debound spring green body.

[0054] 4. Sintering: Put the degummed spring blank together with the sintering fixture into a sintering device (e.g. graphite crucible or sintering furnace), flush in inert gas (nitrogen or argon), and keep the temperature at 1200-1900 °C (preferably 1300-1800 °C, preferably 1400-1700 °C, preferably 1500-1600 °C) and the pressure at 0.9-6 MPa (preferably 1.01-5.5 MPa, more preferably 1.3-5 MPa, more preferably 1.5-4.5 MPa, more preferably 1.8-4 MPa, more preferably 2-3 MPa) for a period of time (e.g. 2-4 hours), and then cool down (e.g. naturally), to obtain the ceramic spring blank.

[0055] Preferably, the method for preparing the ceramic spring further comprises:

[0056] 5. Processing of the ceramic spring

[0057] Cut and polish the ceramic spring horizontally, and polish the surface of the ceramic spring, to finally form the ceramic spring.

[0058] Preferably, the drying mold for the spring blank is a drying mold with helical teeth, the inside of the mold is hollow, and there are a large number of regularly arranged air holes on the helical teeth of the mold.

[0059] Preferably, the drying and shaping mold has been coated with a layer of silicone oil on its surface before use.

[0060] Preferably, in step 2.1, the moisturizing oil agent comprises or consists essentially of a mixture of water-soluble organic solvent and silicone oil. The weight ratio (or mass ratio) of water-soluble organic solvent and silicone oil is 0.1-10:1, preferably 0.2-5:1, preferably 0.25-4:1, preferably 0.333-3:1, preferably 0.4-2.5:1, preferably 0.5-2:1, preferably 0.666-1.5:1, preferably 0.75-1.2:1, preferably 0.8-1.25:1, preferably 0.9-1.1:1, such as 1:1.

[0061] The water-soluble organic solvent is one selected from the group consisting of organic polyol (I), organic polyol monoalkyl ether (II) and nitrogen-containing organic solvent (III), or a mixture of any two or more of organic polyol (I), organic polyol monoalkyl ether (II) and (water-soluble) nitrogen-containing organic solvent (III):

[0062] Organic polyol (I): ethylene glycol, propylene glycol, 1,2-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 1,2,6-hexanetriol, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 2,4-pentanediol, 2-methyl-1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 1,2-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 2-ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, tetraethylene glycol, or glycerol;

[0063] Organic polyol monoalkyl ether (II): ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-n-pentyl ether, ethylene glycol mono-n-hexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol-n-butyl ether, propylene glycol-tert-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol-n-hexyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol-n-butyl ether, dipropylene glycol-tert-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol mono-n-butyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol mono-n-propyl ether, tripropylene glycol-n-butyl ether, tripropylene glycol-tert-butyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol mono-n-propyl ether, tetraethylene glycol mono-n-butyl ether, tetrapropylene glycol monomethyl ether, tetrapropylene glycol monoethyl ether, tetrapropylene glycol mono-n-propyl ether, tetrapropylene glycol-n-butyl ether, tetrapropylene glycol-tert-butyl ether, ethylene glycol phenyl ether, or propylene glycol phenyl ether;

[0064] (Water-soluble) nitrogen-containing organic solvent (III): N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, N-methylpyrrolidone, ε-caprolactam, N-methylformamide, or N,N-dimethylformamide.

[0065] Preferably, the water-soluble organic solvent is glycerol, ethylene glycol, and / or diethylene glycol.

[0066] For the silicone oil, any silicone oil that exhibits a liquid state at room temperature can be used in the present application.

[0067] More specifically, in the above-described method for producing a ceramic spring, in which a multi-stage drying is employed to avoid cracking of the green body surface, the method for producing a ceramic spring comprises the following steps:

[0068] 1. Preparation of a ceramic spring wet green body

[0069] The silicon nitride powder as a ceramic raw material, and a sintering aid (which is selected from one or more of ytterbium oxide powder, magnesium oxide powder, aluminum oxide powder, lanthanum oxide powder, yttrium oxide powder) are mixed by planetary grinding for 36-72 hours, and then placed in an internal mixer to add a binder, a dispersant, and deionized water to mix thoroughly to form a plastic and moisture retaining mud segment. After aging for 36-72 hours, the mud segment is formed into a wire by an extrusion device and simultaneously spiral-wound on a dry shaping mold to form a ceramic spring wet blank. The shaping mold needs to be coated with a layer of silicone oil on the surface before use.

[0070] 2. Drying and shaping of the ceramic spring green body

[0071] (2.1) Impregnation of the moisture-retaining oil

[0072] The prepared ceramic spring wet blank is immersed in a mixture of glycerol and silicone oil in a mass ratio of 1:1 for 2-3 hours, and then taken out and placed in a cool place to allow the excess moisture-retaining oil to drip and form an oil film on the surface of the wet blank.

[0073] (2.2) Film coating

[0074] After the oil film is formed on the surface of the ceramic wet blank, a small amount of water is separated from the ceramic wet blank, the ceramic spring wet blank is simply hardened on the surface, a layer of high-elastic plastic film is attached to the ceramic surface, and the spring wet blank is bound to not undergo structural deformation.

[0075] (2.3) Multi-stage drying

[0076] The ceramic spring bound by the high-elastic plastic film is inserted into a constant-temperature and constant-humidity fan rubber tube together with the mold, and multi-stage drying is performed with flowing gas at different temperatures and different humidities.

[0077] First stage: humidity 80%-90%, temperature 10-20°C, air drying for 8-12 hours, and the body is hardened.

[0078] Second stage: humidity 50%-70%, temperature 20-40°C, air drying for 5-6 hours, and the body shrinks significantly; the temperature can be appropriately reduced during this process to slow down the shrinkage rate.

[0079] Third stage: humidity 20%-40%, temperature 40-60°C, air drying for 2-3 hours, and the spring body is basically dried and the surface high-elastic plastic film is removed.

[0080] Fourth stage: placed in an oven at a temperature of 60-70°C for air drying for more than 2 hours (for example, 2-30 hours, such as 3-20 hours or 4-10 hours), until the water in the spring green body is completely dried.

[0081] (2.4) Demolding (removing the mold)

[0082] Demoulding (stripping or demolding) to form a green ceramic spring.

[0083] 3. Spring stripping

[0084] The green ceramic spring is placed into a sintering fixture and fixed, and then air stripping is performed at a temperature range of 100-700°C to obtain a spring stripping body.

[0085] 4. Sintering: the spring stripping body is placed into a graphite crucible together with the sintering fixture, and an inert gas (nitrogen or argon) is flushed in, the atmosphere pressure is 0.9-6 MPa, the sintering temperature is 1200-1900°C, the holding time is 2-4 h, and natural cooling is performed. A ceramic spring blank is obtained.

[0086] Preferably, the above method for preparing a ceramic spring further comprises:

[0087] 5. Processing of the ceramic spring

[0088] The two ends of the ceramic spring are cut and horizontally polished, and the surface of the ceramic spring is polished and polished, to finally form a ceramic spring.

[0089] Preferably, in step 1 of the above method for preparing a ceramic spring, the relative amounts of the components are:

[0090] Ceramic powder: 72-90 parts by weight, preferably 74-88 parts by weight, preferably 75-87 parts by weight, preferably 78-85 parts by weight, preferably 80-83 parts by weight, such as 81 or 82 parts by weight;

[0091] Sintering aid: 10-16 parts by weight, preferably 11-15 parts by weight, preferably 12-14 parts by weight, such as 13 parts by weight;

[0092] Binder: 8-12 parts by weight, preferably 9-11 parts by weight, such as 10 parts by weight;

[0093] Dispersant: 2-7 parts by weight, preferably 3-6 parts by weight, preferably 4-5 parts by weight; and

[0094] Water: 35-45 parts by weight, preferably 36-44 parts by weight, preferably 37-43 parts by weight, preferably 38-42 parts by weight, preferably 39-41 parts by weight, such as 40 parts by weight.

[0095] Preferably, the raw materials used in the present application are:

[0096] The ceramic powder is silicon nitride powder and / or yttrium-stabilized zirconium oxide powder.

[0097] The sintering aid is one or two or more selected from among ytterbium oxide powder, magnesium oxide powder, aluminum oxide powder, lanthanum oxide powder, and yttrium oxide powder. For example, ytterbium oxide powder + magnesium oxide powder, magnesium oxide powder + aluminum oxide powder, aluminum oxide powder + lanthanum oxide powder, lanthanum oxide powder + yttrium oxide powder, ytterbium oxide powder + aluminum oxide powder, ytterbium oxide powder + magnesium oxide powder + aluminum oxide powder, ytterbium oxide powder + magnesium oxide powder + aluminum oxide powder + lanthanum oxide powder, ytterbium oxide powder + magnesium oxide powder + aluminum oxide powder + lanthanum oxide powder + yttrium oxide powder.

[0098] The binder is one or more selected from among carboxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, gum arabic, gelatin, and starch.

[0099] The dispersant is one or two or more selected from among polycarboxylic acid ammonium salt, polyvinyl alcohol (PVA) and copolymers thereof, polyvinylpyrrolidone (PVP) and copolymers thereof, polyethylene glycol (PEG) and copolymers thereof [for example, polyethylene glycol-polypropylene glycol copolymer (PEG-PPG)], polyethylene oxide and copolymers thereof, polypropylene glycol (PPG) and copolymers thereof, water-soluble phenol-formaldehyde resin, water-soluble polyurethane resin, water-soluble polyacrylate (for example, polyhydroxymethyl acrylate or polyhydroxyethyl methacrylate) and copolymers thereof, polyacrylamide and copolymers thereof (for example, acrylamide, N,N'-methylenebisacrylamide, sodium acrylsulfonate, tetramer copolymer of acrylic acid), polyvinylimidazole and copolymers thereof, polyvinylimidazoline and copolymers thereof, polystyrene sulfonic acid and copolymers thereof, poly(2-acrylamido-2-methyl-1-propanesulfonic acid) and copolymers thereof, polyvinylphosphonic acid and copolymers thereof, poly(N-hydroxyethyl acrylamide) and copolymers thereof, polyaspartic acid and copolymers thereof, polyacrylate and copolymers thereof (for example, acrylic acid / maleic anhydride copolymer), polymaleic anhydride and copolymers thereof, polymaleate and copolymers thereof, polyquaternary ammonium salt (for example, polydiallyldialkylammonium chloride, polyacrylamidoalkylammonium chloride, polyacryloyloxyalkylammonium chloride, polydiallylpropyldimethylammonium chloride, or polymethacryloyloxyethyltrimethylammonium chloride) and copolymers thereof, polyamide acid salt (for example, polyamide acid triethylamine salt) and copolymers thereof, or polyvinylpyridine and copolymers thereof.

[0100] Preferably, the dispersant is polycarboxylic acid ammonium salt, for example, polyacrylic acid ammonium salt or an aqueous solution thereof (concentration 10-60 wt%, such as 20-57 wt%, 30-55 wt%, or 40-50 wt%).

[0101] According to a second aspect of the present application, there is provided a ceramic spring obtained by the above-mentioned method for producing a ceramic spring.

[0102] In the first aspect or the second aspect of the present application, the surface roughness of the ceramic spring is below 1.8 μm, preferably below 1.4 μm or below 1.0 μm, preferably below 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5 μm, 0.45 or 0.4 μm according to GB / T 13841-92. The percentage of the ceramic spring with surface micro-pore defects (i.e. the rejection rate) is below 0.2%, especially below 0.1%.

[0103] The relative density of the ceramic spring is above 96.5%, preferably above 96.6%, above 96.7%, above 96.8%, above 96.9%, above 97%, above 97.1%, above 97.2%, above 97.3%, above 97.4%, above 97.5%, above 97.6%, above 97.7%, above 97.8%, above 97.9%, above 98%, above 98.1%, above 98.2%, above 98.3%, above 98.4%, above 98.5%, above 98.6%, above 98.7%, above 98.8%, above 98.9%, above 99% according to GB / T 2595-2010.

[0104] The rigidity of the ceramic spring is 6-23 N / mm, preferably 7-22 N / mm, preferably 10-21 N / mm, preferably 12-20 N / mm, preferably 15-19 N / mm according to GB / T 1239.2-2009. After the thermal shock test at 1000℃, the rigidity value of the ceramic spring decreases by less than 10%, preferably less than 8%, preferably less than 6%, preferably less than 4%.

[0105] The bending strength of the ceramic spring is 600-770 MPa, preferably 620-765 MPa, preferably 630-760 MPa, preferably 640-755 MPa, preferably 650-750 MPa, preferably 660-745 MPa, preferably 670-740 MPa according to GB / T 6569-2006.

[0106] In addition, the mass change rate of the ceramic spring is below 1% at 1500℃ for 20 hours according to GB / T 32329-2015.

[0107] In the third aspect of the present application, the ceramic spring is applied to the fields of aerospace, new energy, national defense and military products, chemical industry and transportation.

[0108] Ceramic spring has excellent high temperature resistance, oxidation resistance and corrosion resistance, and is often used in extreme environments where metal springs cannot be used, such as aerospace, new energy, national defense, chemical industry and transportation. The ceramic spring is used in the high-temperature environment, for example, the engine and the battery.

[0109] In the field of aerospace, when the space shuttle flies at a speed of 5 Mach, the surface temperature can reach 1280°F at the highest, so in order to prevent high temperature from being conducted from the surface of the aircraft to the inside, the heat sealing system is a necessary and very critical structure, which is widely used in manned spacecraft, supersonic aircraft, space shuttles and reusable launch vehicles, and the heat sealing system is composed of complex mechanical elements, including elastic elements, the working temperature of which is above 800 DEG C, and metal materials cannot meet the long-time use condition, so the ceramic spring is adopted to meet the demand of the heat sealing elastic element.

[0110] In the field of new energy, there are three main ways to fasten the flat SOFC / SOEC, including external pressure equipment fastening, bolt fastening and spring self-tightening fastening. SOFC / SOEC will expand under high-temperature working condition, increase the bolt pressure, and the bolt fastening cannot adjust the pressure, so that the screw rod is stretched and strained, after thermal cycle, the battery piece restores to normal temperature size, the pressure of the battery stack is reduced, the use of the battery stack is affected, and the service life of the battery is reduced. The external pressure equipment can realize free adjustment of the pressure of the battery stack at high and low temperatures, and prolong the service life of the SOFC / SOEC, but the servo press and high-temperature steel support are expensive and cannot be popularized. The spring self-tightening fastening can realize self-regulation of the internal pressure of the battery stack during the thermal cycle process, keep the single battery piece closely attached for a long time, avoid the breakage of the battery piece due to excessive expansion pressure, prolong the service life of the battery, and compared with the external pressure equipment, the ceramic spring is used as the SOFC self-tightening part, the volume of the battery stack is effectively reduced, the servo press and high-temperature steel support are provided for each battery stack, and the price is expensive, while the price of the spring is relatively low. In the field of chemical equipment, the ceramic spring can be used to prepare pressure regulating valves for corrosive or high-temperature gas and liquid.

[0111] The application can effectively control the spring structure precision and achieve the ideal spring performance. The spring green body is placed to occur surface dry cracking and wire fracture, and the spring structure is more beneficial to be maintained during the sintering process of the spring.

[0112] Compared with the prior art, the application has the following beneficial effects:

[0113] 1. The spring green body is impregnated with a moisturizing oil agent. After impregnation, the spring green body will undergo simple water analysis, causing the spring green body to undergo preliminary hardening and reduce the humidity of the green body, which provides good support for the use of high-elastic plastic film in the following step to prevent wire deformation. The moisturizing oil agent forms an oil film on the surface of the spring after impregnation, which effectively prevents the rapid loss of moisture and prevents the external and internal moisture of the wire from causing breakage.

[0114] 2. For spring coating, high-elastic plastic film can bind the spring green body structure and prevent the spring green body from peeling off during drying on the mold, causing the spring structure to deform. Secondly, it can create a constant temperature and humidity environment in the film binding environment, which is conducive to precise control of the environment. Finally, the rapid loss of moisture on the surface of the spring wire causes the spring green body surface to crack.

[0115] 3. The key point of the multi-stage drying of the spring is that the spring green body drying mold is hollow and has regular arranged air holes on the spiral teeth, which is conducive to constant temperature and ventilation drying of the spring green body. Multi-stage drying is conducive to uniform shrinkage of the spring green body without cracking, greatly reducing the spring green body drying scrap rate, which is less than 0.1%.

[0116] The method of the present application improves the drying effect of the green body, prevents the shrinkage and cracking of the ceramic green body, and realizes the precise control of the shape and size of the ceramic. BRIEF DESCRIPTION OF DRAWINGS

[0117] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments of the present application will be described below.

[0118] Figure 1 A schematic diagram of a resin-based ceramic spring mold prepared by using light-curing printing.

[0119] Reference signs:

[0120] 1: hollow mold; 2: air hole.

[0121] Figure 2 A photo of the ceramic spring product of embodiment 1 of the present application. DETAILED DESCRIPTION

[0122] In order to make the purpose, technical solutions and advantages of the present application more clear, the following will describe each aspect involved in the present application in detail with specific embodiments.

[0123] Preparation of spring drying and shaping mold

[0124] Spring drying mold, namely photocuring printing resin base mold, is a resin base ceramic spring mold prepared by photocuring printing method, see photocuring printing resin base mold (patent application CN 114874396 A). The preparation method is as follows:

[0125] (1) 10%-20% (such as 15wt%) of bisphenol A-glycidyl dimethacrylate, 20%-30% (such as 25wt%) of bisphenol A epoxy acrylate, 20%-40% (such as 30wt%) of first monomer and 20%-30% (such as 25wt%) of second monomer are mixed uniformly to obtain a first mixture. The first monomer includes one or more of hydroxyethyl methacrylate, hydroxypropyl methacrylate, and cyclotrimethylolpropane formal acrylate, and the second monomer includes one or more of ethylene glycol dimethacrylate, dipentaerythritol hexaacrylate, and trishydroxymethylpropane tetraacrylate.

[0126] (2) 1%-5% (such as 3wt%) of a photoinitiator, 0.1%-1% (0.5wt%) of a UV absorber, 0.1%-1% (0.5wt%) of a polymerization inhibitor and 0.01%-1% (0.5wt%) of a defoaming agent are added to the first mixture, heated at 40-50°C for 15-25 minutes, and mixed uniformly to obtain a second mixture. The photoinitiator includes one or more of bis(2,4,6-trimethylbenzoyl)-phenyl phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-1-propanone, the UV absorber includes one or more of UV-531 and UV-P, and the polymerization inhibitor includes one or more of active amine and N,N-dimethylbenzoic acid ethyl ester.

[0127] (3) 10%-30% of silica powder is added to the second mixture and mixed uniformly to obtain a photosensitive resin.

[0128] (4) The resin is placed into a light curing 3D printer tank, a ceramic spring drying three-dimensional model is introduced, a release film is pasted on the printing platform, the 3D printing equipment parameters are adjusted, the energy density is set to 2-8 mw / cm 2 , the exposure time is set to 3-5s, the lifting speed is set to 1-4mm / s, the lowering speed is set to 1-6mm / s, the printing layer thickness is set to 10-100μm, and the printing is started. After printing for 3-10 hours, a ceramic spring drying mold is obtained, as shown in Figure 1 .

[0129] Example 1

[0130] A preparation method of a ceramic spring includes the following steps:

[0131] 1. Preparation of ceramic spring wet blank

[0132] Take 72 parts by weight of silicon nitride powder, 10 parts by weight of ytterbium oxide powder and magnesium oxide powder (the weight ratio of the two is 7.2:1) as sintering aids, and grind them for 36 hours by a planetary mill, mix thoroughly, then add 8 parts by weight of carboxymethyl cellulose as a binder, 2 parts by weight of polyammonium carboxylate as a dispersant (i.e. an aqueous solution of polyammonium acrylate, concentration 45 wt%), and 35 parts by weight of deionized water to mix (form a mud section), and let it stand for 36 hours to obtain a ceramic plastic mud. The ceramic plastic mud is formed into a wire by an extrusion device (polypropylene pipe), and is synchronously spiral-wound on a dry shaping mold (as shown in Figure 1

[0133] 2. Dry shaping of the green body of the ceramic spring

[0134] (2.1) Impregnation of the moisturizing oil agent

[0135] The prepared ceramic spring wet body is immersed in a mixture of glycerol and silicon oil with a mass ratio of 1:1 for 2-3 hours, and then taken out and placed in a cool place to allow the excess moisturizing oil agent to drip off, so as to form an oil film on the surface of the wet body.

[0136] (2.2) Film coating

[0137] After the oil film is formed on the surface of the ceramic wet body, a small amount of water is separated out, the ceramic spring wet body is simply hardened on the surface, and a thin film of high-elastic plastic (polyethylene film) is attached to the ceramic surface to constrain the spring wet body from structural deformation.

[0138] (2.3) Multi-stage drying

[0139] The ceramic spring constrained by the high-elastic plastic film is inserted into the rubber tube of a constant-temperature and constant-humidity fan, and is subjected to multi-stage drying of flowing gas with different temperatures and different humidities:

[0140] First stage: humidity 85%, temperature 15°C, air-drying for 10 hours, and the body is hardened.

[0141] Second stage: humidity 60%, temperature 30°C, air-drying for 6 hours, and the body is significantly shrunk; the temperature can be appropriately reduced during this process to slow down the shrinkage rate.

[0142] Third stage: humidity 30%, temperature 50°C, air-drying for 2.5 hours, and the spring body is basically dried, and the surface high-elastic plastic film is removed.

[0143] ​Fourth segment: Put into the oven, at a temperature of 65℃, ventilation drying 5 hours, until the spring green body inside the moisture is completely dried.

[0144] (2.4) Demoulding (removing the mould)

[0145] Removing the mould (demoulding or demoulding), forming a ceramic spring green body.

[0146] 3. Ceramic spring degassing

[0147] Put the ceramic spring green body into the sintering fixture and fix it, then put it into the vacuum degassing furnace for degassing, at a degassing temperature of 550℃ and a vacuum degree of 1×10 1 Pa, air degassing, degassing time is 20 hours, to get spring degassing body.

[0148] 4. Sintering: Put the spring degassing body together with the sintering fixture into the graphite crucible, flush with inert gas (nitrogen or argon), atmosphere pressure is 2MPa, sintering temperature is 1200℃, holding for 3 hours, then natural cooling. Get ceramic spring blank.

[0149] 5. Processing of ceramic spring

[0150] Cut and polish the ceramic spring at both ends, and polish the surface of the ceramic spring, finally form the ceramic spring.

[0151] The ceramic spring prepared in Example 1 has high density, the relative density is 98.1%; the surface smoothness is high, the surface gloss is good, the surface roughness is 0.6μm; the size error is small, the batch stability is good; the stiffness is 13.5N / mm, after 1000℃ thermal shock test, the stiffness value decreases less than 7.5%; under the condition of 1500℃ oxidation for 20 hours, the weight gain rate of the ceramic spring is 0.8%, the oxidation resistance is excellent; the bending strength is 645MPa.

[0152] In step 2, the spring body drying waste rate is less than 0.01%.

[0153] The method of this example improves the drying effect of the body, prevents the shrinkage deformation and cracking of the ceramic body, and realizes the accurate control of the shape and size of the ceramic.

[0154] Comparative Example 1

[0155] Repeat Example 1, except that the drying method is different from (2.3) multi-stage drying in Example 1, but the following drying method is used:

[0156] The ceramic spring, which has been bound by the high-elastic plastic film, is inserted into the rubber tube of the constant temperature and humidity fan along with the mold. After being dried for 10 hours under the constant temperature and humidity conditions of 80% humidity and 20°C, the moisture is partially removed, and the first-stage drying process is completed. Then, the ceramic spring is placed in an oven and dried for 10 hours at a temperature of 300°C, and the second-stage drying process is completed. After demolding, the ceramic spring blank is obtained.

[0157] After the demolding step (2.4), the spring blank drying waste rate is 0.5%.

[0158] Comparative Example 2

[0159] Example 1 is repeated, except that the step (2.1) of impregnating the moisturizing oil agent is omitted.

[0160] After the demolding step (2.4), the spring blank drying waste rate is 0.8%.

[0161] The surface roughness of the ceramic spring obtained in Comparative Example 2 is 1.3 μm.

[0162] Comparative Example 3

[0163] Example 1 is repeated, except that the step (2.2) of coating is omitted, and then the step (2.3) of multi-stage drying is performed.

[0164] The ceramic spring, which has not been coated, is inserted into the rubber tube of the constant temperature and humidity fan along with the mold, and the step (2.3) of multi-stage drying is performed.

[0165] After the demolding step (2.4), the spring blank drying waste rate is 1.2%.

[0166] The surface roughness of the ceramic spring obtained in Comparative Example 3 is 1.0 μm.

[0167] In summary, through the synergistic effect of the three technical means of impregnating the moisturizing oil agent, coating, and multi-stage drying, the spring blank drying waste rate is greatly reduced, and the surface is smoother.

Claims

1. A method for preparing a ceramic spring, comprising the following steps: 1) Preparation of a ceramic spring green body ceramic powder and sintering aids are ground together in a mill, and then the ground mixture is placed in a mixing device (e.g., an internal mixer) and mixed thoroughly with the addition of a binder, a dispersant, and water to form a ceramic slurry, which is aged (e.g., for 36-72 hours, such as 40-60 hours, or 50-55 hours) and then formed into a wire by an extrusion device and simultaneously spiral-wound on a drying mold to form a ceramic spring green body; 2) Drying and shaping of the ceramic spring green body (2.1) Impregnation with a moisturizing oil the ceramic spring green body obtained in step 1 is impregnated with a moisturizing oil (e.g., for 2-3 hours) together with the mold, removed, and left to dry in a cool place, thereby forming an oil film on the surface of the green body; I (2.2) Film coating a thin film of a high-elasticity plastic (e.g., a polyethylene film or an ethylene-propylene copolymer film) is attached to the surface of the ceramic spring green body to bind the green body and prevent structural deformation; (2.3) Multi-stage drying the ceramic spring green body bound by the thin film of high-elasticity plastic is inserted into a rubber tube of a constant-temperature and constant-humidity chamber (e.g., a constant-temperature and constant-humidity fan) together with the mold, and then subjected to multi-stage drying (in which drying is performed in a flowing gas atmosphere at different humidity and different temperatures in different stages): first stage: air-drying at a humidity of 80-90% and a temperature of 10-20°C (e.g., for 8-12 hours, such as 10 hours) to allow the green body to harden; second stage: air-drying at a humidity of 50-70% and a temperature of 20-40°C (e.g., for 5-6 hours) to allow the green body to shrink significantly; the temperature can be moderately lowered during this process to slow the rate of shrinkage; third stage: air-drying at a humidity of 20-40% and a temperature of 40-60°C (e.g., for 2-3 hours) to obtain a substantially dried ceramic spring green body; the thin film of high-elasticity plastic on the surface of the green body is removed; fourth stage: the substantially dried ceramic spring green body is placed in an oven and air-dried at a temperature of 60-70°C (e.g., for 2-30 hours, such as 3-10 hours or 5-20 hours) until the moisture inside the spring green body is completely dried; (2.4) Demolding the mold is removed to form a ceramic spring green body; 3) Removal of binder from the ceramic spring the ceramic spring green body is fixed in a sintering jig and placed in a binder removal furnace (at a temperature in the range of 100-700°C, preferably 150-650°C, more preferably 200-600°C) to perform air binder removal, thereby obtaining a binder-removed spring green body; 4) Sintering The degreased spring blank is placed in a sintering device (e.g. graphite crucible or sintering furnace) together with a sintering fixture, flushed with an inert gas (nitrogen or argon), and held at an atmosphere pressure of 0.9-6 MPa (preferably 1.01-5.5 MPa, more preferably 1.3-5 MPa, more preferably 1.5-4.5 MPa, more preferably 1.8-4 MPa, more preferably 2-3 MPa) and a sintering temperature of 1200-1900°C (preferably 1300-1800°C, preferably 1400-1700°C, preferably 1500-1600°C) for a period of time (e.g. 2-4 hours), and then cooled (e.g. by natural cooling) to obtain a ceramic spring blank.

2. The method according to claim 1, wherein the method further comprises the following steps: 5) Machining of the ceramic spring The ceramic spring is cut and polished at both ends and the surface of the ceramic spring is polished to form the ceramic spring.

3. The method according to claim 1 or 2, wherein the dry shaping mold has been coated with a silicone oil coating on its surface before use; and / or The dry shaping mold is a dry mold with helical teeth, the inside of the mold is hollow, and a large number of regularly arranged air holes are provided on the helical teeth of the mold.

4. The method according to any one of claims 1-3, wherein, In step 2.1, the moisturizing oil agent comprises or consists essentially of a mixture of a water-soluble organic solvent and silicone oil; preferably, the weight ratio of the water-soluble organic solvent and silicone oil is 0.1-10:1, preferably 0.2-5:1, preferably 0.25-4:1, preferably 0.333-3:1, preferably 0.4-2.5:1, preferably 0.5-2:1, preferably 0.666-1.5:1, preferably 0.75-1.2:1, preferably 0.8-1.25:1, preferably 0.9-1.1:1, such as 1:

1.

5. The method of claim 4, wherein, The water-soluble organic solvent is one selected from the group consisting of organic polyols (I), organic polyol monoalkyl ethers (II) and nitrogen-containing organic solvents (III), or is a mixture of any two or more selected from the group consisting of organic polyols (I), organic polyol monoalkyl ethers (II) and water-soluble nitrogen-containing organic solvents (III): organic polyols (I): ethylene glycol, propylene glycol, 1,2-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 1,2,6-hexanetriol, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 2,4-pentanediol, 2-methyl-1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 1,2-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 2-ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, tetraethylene glycol or glycerol; organic polyol monoalkyl ethers (II): ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol mononormal butyl ether, ethylene glycol mononormal pentyl ether, ethylene glycol mononormal hexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mononormal propyl ether, propylene glycol-normally butyl ether, propylene glycol-tert-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mononormal propyl ether, diethylene glycol mononormal butyl ether, diethylene glycol-normally hexyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mononormal propyl ether, dipropylene glycol-normally butyl ether, dipropylene glycol-tert-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol mononormal butyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol mononormal propyl ether, tripropylene glycol-normally butyl ether, tripropylene glycol-tert-butyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol mononormal propyl ether, tetraethylene glycol mononormal butyl ether, tetrapropylene glycol monomethyl ether, tetrapropylene glycol monoethyl ether, tetrapropylene glycol mononormal propyl ether, tetrapropylene glycol-normally butyl ether, tetrapropylene glycol-tert-butyl ether, ethylene glycol phenyl ether, or propylene glycol phenyl ether; water-soluble nitrogen-containing organic solvent (III): N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, N-methylpyrrolidone, ε-caprolactam, N-methylformamide, or N,N-dimethylformamide.

6. The method of claim 5, wherein, The water-soluble organic solvent is glycerol, ethylene glycol, and / or diethylene glycol.

7. The method of any of claims 1-6, wherein, The relative amounts of the components are: ceramic powder: 72 to 90 parts by weight, preferably 74 to 88 parts by weight, preferably 75 to 87 parts by weight, preferably 78 to 85 parts by weight, preferably 80 to 83 parts by weight, such as 81, 82 parts by weight; sintering aid: 10 to 16 parts by weight, preferably 11 to 15 parts by weight, preferably 12 to 14 parts by weight, such as 13 parts by weight; binder: 8 to 12 parts by weight, preferably 9 to 11 parts by weight, such as 10 parts by weight; dispersant: 2 to 7 parts by weight, preferably 3 to 6 parts by weight, preferably 4 to 5 parts by weight; and water: 35 to 45 parts by weight, preferably 36 to 44 parts by weight, preferably 37 to 43 parts by weight, preferably 38 to 42 parts by weight; preferably 39 to 41 parts by weight, such as 40 parts by weight.

8. The method according to claim 7, wherein the ceramic powder is silicon nitride powder and / or yttrium-stabilized zirconium oxide powder; and / or the sintering aid is one or two or more selected from the group consisting of ytterbium oxide powder, magnesium oxide powder, aluminum oxide powder, lanthanum oxide powder, and yttrium oxide powder; and / or the binder is one or more selected from the group consisting of carboxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, gum arabic, gelatin, and starch; and / or the dispersant is one or more selected from the group consisting of sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene castor oil fatty acid ester sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium The dispersant is one or two or more selected from the group consisting of polycarboxylic acid ammonium salt, polyvinyl alcohol (PVA) and its copolymer, polyvinyl pyrrolidone (PVP) and its copolymer, polyethylene glycol (PEG) and its copolymer [for example, polyethylene glycol-polypropylene glycol copolymer (PEG-PPG)], polyethylene oxide and its copolymer, polypropylene glycol (PPG) and its copolymer, water-soluble phenolic resin, water-soluble polyurethane resin, water-soluble polyacrylate (for example, polyhydroxymethyl acrylate or polyhydroxyethyl methacrylate) and its copolymer, polyacrylamide and its copolymer (for example, acrylamide, N,N'-methylene bisacrylamide, sodium acrylsulfonate, tetramer copolymer of acrylic acid), polyvinylimidazole and its copolymer, polyvinylimidazoline and its copolymer, polystyrene sulfonic acid and its copolymer, poly(2-acrylamido-2-methyl-1-propanesulfonic acid) and its copolymer, polyvinylphosphonic acid and its copolymer, poly(N-hydroxyethyl acrylamide) and its copolymer, polyaspartic acid and its copolymer, polyacrylate and its copolymer (for example, acrylic acid / maleic anhydride copolymer), polymaleic anhydride and its copolymer, polymaleate and its copolymer, polyquaternary ammonium salt (for example, polydiallyl dialkyl ammonium chloride, polyacrylamido alkyl ammonium chloride, polyacryloxy alkyl ammonium chloride, polydiallyl dimethyl ammonium chloride, or poly(methacryloyloxyethyl) trimethyl ammonium chloride) and its copolymer, polyamide acid salt (for example, polyamide acid triethylamine salt) and its copolymer, or polyvinylpyridine and its copolymer; preferably, the dispersant is polycarboxylic acid ammonium salt, for example, polyacrylic acid ammonium salt or its aqueous solution (concentration 10-60 wt%, such as 20-57 wt%, 30-55 wt% or 40-50 wt%).

9. A ceramic spring obtained by the method according to any one of claims 8; Preferably, the surface roughness of the ceramic spring is below 1.8 μm, preferably below 1.4 μm or below 1.0 μm, preferably below 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5 μm, 0.45 or 0.4 μm according to GB / T 13841-92; Preferably, the percentage of ceramic springs having surface micro-pore defects is below 0.2%, in particular below 0.1%; Preferably, the relative density of the ceramic spring is above 96.5%, preferably above 96.6%, above 96.7%, above 96.8%, above 96.9%, above 97%, above 97.1%, above 97.2%, above 97.3%, above 97.4%, above 97.5%, above 97.6%, above 97.7%, above 97.8%, above 97.9%, above 98%, above 98.1%, above 98.2%, above 98.3%, above 98.4%, above 98.5%, above 98.6%, above 98.7%, above 98.8%, above 98.9%, above 99% according to GB / T 2595-2010; Preferably, the rigidity of the ceramic spring is 6-23 N / mm, preferably 7-22 N / mm, preferably 10-21 N / mm, preferably 12-20 N / mm, preferably 15-19 N / mm according to GB / T 1239.2-2009; Preferably, the rigidity value of the ceramic spring decreases by less than 10%, preferably less than 8%, preferably less than 6%, preferably less than 4% after 1000℃ thermal shock test; Preferably, the bending strength of the ceramic spring is 600-770 MPa, preferably 620-765 MPa, preferably 630-760 MPa, preferably 640-755 MPa, preferably 650-750 MPa, preferably 660-745 MPa, preferably 670-740 MPa according to GB / T 6569-2006; Preferably, the absolute value of the mass change rate of the ceramic spring is less than 1% under the condition of oxidation at 1500℃ for 20 hours according to GB / T 32329-2015.

10. The use of the ceramic spring according to claim 9, which is applied to the fields of aerospace, new energy, national defense and military products, chemical industry, and transportation.

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